Modern cellular telephones or mobile stations employ or are proposed to employ a lock code or service programming code (SPC) to enable or activate certain features or to enable service to the mobile station from a certain carrier or service provider. By example, if a certain service provider were to provide a mobile station to a user as an incentive to subscribe to the service provider's network, then the service provider would wish to prevent the user from obtaining service with a competing service provider.
The SPC should fulfil at least the following requirements. First, it should be determinable in accordance with some type of algorithm. Second, the SPC of each mobile station should be unique. Third, the carrier must know the unique SPC of each mobile station. Fourth, the security of SPC should be maintained so as to prevent unauthorized persons from learning the SPC. Fifth, the data management requirements of the service provider should be minimal with regards to the SPC.